The prior art extensively discloses methylenethiol type collagenase inhibitors:
i. Biochem, Biophys. Res. Commun. 101, 1251 (1981). PA0 ii. U.S. Pat. Nos. 4,374,765; 4,371,465; 4,235,885; 4,297,275; 4,327,111; 4,382,081; 4,242,354. PA0 iii. Gt. Brit. No. 2,092,574; Gt. Brit. No. 2,090,591.
It has been discovered that modification of the structure of the prior art compounds by introduction of a substituent on the methylenethiol carbon so that the thiol moiety is adjacent an assymetric center surprisingly increases the ability of the compounds of the prior art or related to the prior art to inhibit collagenase.
For example, the ability of the prior art compounds described as A, B, and C below to inhibit mammalian collagenase is greatly increased by changing ##STR2## i.e. forming an assymetric center adjacent the thiol in accordance with the present invention.
More specifically, compounds of the following formulae A, B, and C are so modified. ##STR3## or salts thereof, wherein
R is hydrogen, alkanoyl of 2 to 10 carbon atoms or arylcarbonyl;
R.sub.1 is lower alkyl of 1 to 10, preferably 1 to 6, carbon atoms, cycloalkyl of 3 to 7 carbon atoms, aryl or arylalkyl;
R.sub.2 is hydrogen, ##STR4##
R.sub.3 is ##STR5##
R.sub.4 is hydrogen, methyl, ethyl, or ##STR6##
R.sub.5 and R.sub.6 are each independently selected as --OCH.sub.3 or --OCH.sub.2 CH.sub.3 or are combined as --OCH.sub.2 CH.sub.2 O-- or --O--(CH.sub.2)--O--;
R.sub.7 and R.sub.8 are each independently selected as hydrogen, methyl or ethyl or are combined as --(CH.sub.2).sub.4 --; --(CH.sub.2).sub.5 -- or --CH.sub.2 CH.sub.2 --O--CH.sub.2 CH.sub.2 --;
R.sub.9 is hydrogen, methyl, ethyl ##STR7##
m is an integer from 0 to 7;
p is an integer from 1 to 3;
AA.sub.n is an amino acid chain of from one to three amino acids;
n is 1 or 1, 2 or 1, 2, 3;
when p is 1, AA.sub.n is AA.sub.1 ;
when p is 2, AA.sub.n is AA.sub.1 --AA.sub.2 ;
when p is 3, AA.sub.n is AA.sub.1 --AA.sub.2 --AA.sub.3 ;
AA.sub.1 is glycine or alanine;
AA.sub.2 is glycine or alanine;
AA.sub.3 is leucine, glutamine or isoleucine.
Likewise compounds of formula B ##STR8## or a salt thereof, wherein
R.sub.1 is hydrogen, alkanoyl or 2 to 10 carbon atoms, or arylcarbonyl;
R.sub.2 is ##STR9## wherein R.sub.4 is hydrogen, alkyl or aryl;
R.sub.3 is alkyl of 3 to 8 carbon atoms, cycloalkyl of 3 to 7 carbon atoms, aryl or arylalkyl; and n is an integer of 1 to 20.
Also compounds of formula C ##STR10## and salts thereof, wherein
R.sub.1 is hydrogen or alkanoyl of 2 to 10 carbon atoms;
R.sub.2 is hydroxy, amino, or ##STR11##
R.sub.3 is hydrogen, alkyl of 1 to 4 carbon atoms. ##STR12##
R.sub.4 is hydroxy, amino, arginine, leucine, glutamine, alanine or glycine; and
m is O or an integer of 1 to 9.
This invention relates to the above-described novel compounds having pharmacological activity, to the production thereof, to compositions containing them, and to their use in the treatment of management of conditions or diseases, e.g., rheumatoid arthritis, in which collagenase promoted collagen breakdown is a causative factor.
The compounds of the invention act as inhibitors of mammalian collagenase which initiates collagen breakdown. Extensive proteolytic enzyme promoted degradation of articular cartilage is associated with joint destruction in rheumatoid arthritis. Collagen is one of the major components of the protein matrix of joint cartilage and bone. Histological observations of rheumatoid lesions have established that such lesions are characterized by the proliferation of synovial lining cells with subsequent neovascularization and infiltration by lymphocytes, macrophages and plasma cells, collectively referred to as soft tissue or "pannus". The importance of such soft tissue in cartilage erosion has been well demonstrated.
Evanson and coworkers, for example, found that large amounts of neutral collagenase are produced by pannus tissue (Evanson, J. M., et al., Arthritis & Rheum., 27, 2639-2651, 1968). More recently, others have confirmed that neutral collagenase plays an important degradative role in the arthritic joints of experimental animals (see Cambray, et al., Rheumatol Int. 1, 11-16 and 17-20, 1981) and in humans (Cawston, et al., Arthritis & Rheum., 27, 285-290, 1984).
A mono-specific antiserum to purified synovial collagenase has been used to localize the enzyme in rheumatoid tissues (Wooley, et al., Eur. J. Biochem. 69, 421-428, 1976). Immunoreactive collagenase was detected in high density at the cartilage-pannus junction (Wooley, et al., Arthritis & Rheumatism, 20, 1231-1349.) Wooley, et al., (Science, 200, 773-775, 1978) have further identified a sub-population of synovial cells responsible for collagenase production.
Thus, the foregoing observations have provided conclusive evidence that collagenase is directly involved in the cartilage erosion process seen in rheumatoid arthritis. Accordingly, the compounds of the present invention which specifically inhibit mammalian collagenase are pharmacologically useful in the treatment of rheumatoid arthritis and related diseases in which collagenolytic activity is a contributing factor, such as corneal ulceration, peridontal disease, tumor invasion, dystrophic epidermolysis bullosa, etc.
These compounds have substantially no angiotensin converting enzyme (ACE)-inhibiting activity. ACE inhibitors are described in European Appl. No. A-0012401. ACE is a carboxydipeptidase--it cleaves a peptide substrate two residues from the C-terminus. Consequently the C-terminal carboxylic acid is a prime recognition site for both substrate and inhibitors; removal of this group drastically reduces inhibitory potency. Collagenase, on the other hand, is an endopeptidase and, as such, has no prerequisite for this binding interaction. Additionally, the structure of collagen differs essentially from angiotensin-I which is a decapeptide and is cleaved at a phenylalanine-histidine bond to give an octapeptide (angiotensin-II and a dipeptide (histidylleucine). Collagen is much more complex, in being a triple helix, each strand of the helix containing of the order of 1,000 amino acid residues, the sequence of amino acids around the site cleaved by collagenase being completely different from that around the cleavage site of Angiotensin I. Collagenase cleaves approximately two-thirds of the way along the chain from the N-terminus. The amide bond which is cleaved by collagenase is either a glycine-leucine or a glycine-isoleucine bond.
For use in the treatment of rheumatoid arthritis or other collagen based degradative diseases, the compounds of this invention may be administered to a mammal in need thereof orally or by injection. The daily total effective dose will generally range between 25 mg. to 750 mg.
The compounds of this invention can be formulated in compositions such as tablets, capsules or elixirs for oral administration or in sterile solutions or suspensions for parenteral administration. About 10 mg., for example, of a compound according to the invention is compounded with a physiologically acceptable vehicle, carrier, excipient, binder, preservative, stabilizer, flavour, etc., in a unit dosage form as called for by accepted pharmaceutical practice. (See for example, Remington's Pharmaceutical Science Mach Publishing Co., Easton, Penn. 1965). The amount of active substance in these compositions or preparations is such that a suitable dosage in the range indicated is obtained.
The compounds according to the invention may be made by methods which are generally known in peptide chemistry for analogous compounds. In particular it is to be understood that reactive groups not involved in a particular reaction (e.g. amino, carboxy, hydroxy etc.,) may be protected by methods standard in peptide chemistry prior to reactions of other groups and subsequently deprotected.
The intermediates of use in the production of the end-products are either known compounds or can be made by known methods, as described in the Examples.